Cancer is the 2nd leading cause of death in the United States. Many people who die, don't even realize they have it until it too late. And treatment only gets harder and more expensive the longer you wait. That's why it is vital for you to know the early warning signs to let your doctor know.

Fatigue or Weakness

Extreme fatigue and weakness that's not cured by rest. This could be a sign of anemia caused by loss of red blood cells from leukemia, colon, or stomach cancer.

As more and more blood cells are lost, there's not enough healthy red blood cells to transport oxygen to the rest of the body.

Unusual Weight Loss or Gain

If you start losing weight, and you haven't changed your diet or exercise, tell your doctor. Loss of appetite can also be because of cancer. As your body tries to fight the cancer naturally, it produces cytokines which decreases appetite.

Some cancers can actually cause weight gain. As an ovarian cancer tumor grows, it can retain fluid which can lead to weight gain. So you need to be alert for any sudden weight gain or loss.

Unusual Shortness of Breath

When you don't have enough oxygen in the blood, you feel short of breath. Your lungs try to compensate by making you breath more.

This could be a sign of lung cancer or leukemia.

Persistent Cough or Hoarseness.

A persistent cough that doesn't go away might be a sign of lung cancer.

Hoarseness might mean that you have a problem with cancer of the larynx or thyroid gland.

Bleeding in Stool or Urine

Blood in your stool could be colon or rectal cancer.

Blood in the urine may be a sign of bladder or kidney cancer.

Discoloration of Skin or Moles

Any wart, mole, or freckle that changes color, size, or shape, or that loses its sharp border should be seen by a doctor right away.

Any skin color change should be told to your doctor right away.

Lump or Swelling

If you notice any new lumps or swelling anywhere on your body, you should see your doctor, especially if the lump is getting bigger or painful.

Areas you should be most on guard for new lumps are breast, testicles, lymph nodes, and other soft tissues on your body.

Headaches

Any long lasting pain that last for three or more weeks you should see your doctor.

Even if it's not cancer you should have it checked out. Acute headaches are a symptom of leukemia.

Sores That Don't Heal

Skin cancers may bleed and never heal. Mouth sores or white patches inside the mouth that persist could be an oral cancer.

Sores on genitalia can also be early warning signs of a cancer.

Fever

Cancer can weaken your immune system, leaving you vulnerable to infections which shows up as fevers.

If you find that you are constantly getting fevers have your doctor check you out.

Yellow Eyes and Jaundice

Your skin and the whites of your eye can change for many reasons, some of them could be very serious even if it's not cancer. Yellowing is often a sign that you are having liver problems.

The liver problems could be from a variety of serious causes, hepatitis, cirrhosis, and several different types of cancer. If you notice that your eyes or skin have changed color, notify your doctor.

Difficulty Swallowing

If you occasionally have problems swallowing, do not panic. Everyone has problems swallowing every now and then, this is normal.

But, if you have difficulty swallowing along with vomiting or weight loss and it lasts for more than a few weeks, then your doctor may want to check for stomach or throat cancer.

Bloating

Like problems with swallowing, every one feels bloated occasionally, especially if they ate a lot or drank a lot of fluids. Bloating is only a warning sign if it's persistent and lasts for several weeks.

A bloated belly could be a sign of ovarian cancer.

Changes in Voice

If you or someone else notices changes in your voice, especially if it gets deeper, hoarser, and raspier, then this could be a cancer sign. Again, this only applies if the voice change lasts for more than a few weeks.

Voice changes can be caused by a lung cancer tumor affecting the nerve that controls the larynx or if you're a woman, it could be ovarian cancer interfering with your hormones.

Swollen Leg

If one of your legs looks or feels swollen for no reason. This could be an indication of cervical cancer.

Typically, a swollen leg by itself isn't a sign of cancer unless you also have pain, unusual discharge, or some other sign of cervical or kidney cancer.

Heavy Night Sweats

Heavy night sweats alone is not a source of concern. But heavy night sweats can be an early indicator of cancers of the lymph nodes.

People who have heavy night sweats caused by cancer usually have other early warning symptoms as well as fevers and unexplained weight loss.

Indigestion and Nausea

Indigestion and nausea can be a symptom of cancer, especially of the esophagus and stomach.

Though most times it's not a source of concern, a doctor should check it out if indigestion and nausea occurs often, it comes on suddenly, or if it's particularly painful, especially if you are over the age of 55. Even if it isn't cancer it could be still be a symptom of something else that is serious, like an ulcer.

Changes in Bladder Control

If you find that your bathroom habits are changing this could an early warning sign for several types of cancer. Problems include over active bladder, problems urinating, or not being able to completely empty your bladder.

This could be an early symptom of cancer of the bladder. Or, if you're a man, it could be a sign of prostate cancer. And if you're a woman, it could mean ovarian or cervical cancer.

Belly Pain That Moves to the Back

The pancreas is a vital organ in digestion It releases many enzymes vital for the breakdown of nutrients. Cancer of the pancreas is extremely serious.

Pancreatic cancer often starts off as belly pain that often over time starts to migrate to the back area.

Abnormalities in Vision

Abnormalities in vision, such as double vision, is serious even if not cancer. It could be a symptom of diabetes, a weakening of the eye muscles, multiple sclerosis, an aneurysm, head injury, or even cancer.

A brain tumor behind the eye, could damage the nerves to the eye muscles causing the double vision.